Apparatus for displaying image informations

ABSTRACT

Disclosed is an apparatus for displaying image informations using a storage tube as a memory device. According to this invention &#39;&#39;&#39;&#39;writing&#39;&#39;&#39;&#39; of informations in the storage tube is performed in the &#39;&#39;&#39;&#39;Semi-random Scanning&#39;&#39;&#39;&#39; mode in which raster scanning is performed in one of the vertical and horizontal directions whereas random scanning is conducted in the other direction.

United States Patent 119 1 MODE SELECTION CT.

BEAM CURRENT CONTROL CT.

BEAM ON/OFF CT.

'Goto et al. 1 Feb. 11, 1975 [54] APPARATUS FOR DISPLAYING IMAGE3,130,397 4/1964 Simmons 340/324 AD N 3,281,822 10/1966 Evans 340/324 ADINFORMATIO u 3,336,498 8/1967 Castanera 340/324 AD 1 Inventors: Eii'chlG010, Futlsawa; H hme 3,380,028 4/1968 Gustafson et al. 340/324 A Ohiwa,Tokyo; Kansei Iwata, 3,514,616 5/1970 Kolb 340/324 AD Tokyo; TadaoUrano, Tokyo, all of Japan Primary Examiner-Donald J. Yusko [73]Assignees: Rlkagaku Kenkyusho, Saitama-ken; Assistant Examiner MarshanM. Curtis hats Elecmc Tokyo Attorney, Agent, or Firm-Bucknam and Archerboth of, Japan [22] Filed: Nov. 24, 1972 [21] Appl. No.: 308,947 [57]ABSTRACT [30] Foreign Application Priority Data Disclosed is anapparatus for displaying image infor- J 4 34 mations us ng a storagetube as a memory device. Ac- NOV. 24, apan t 8 cording to inventionwriting of informations in t the storage tube is performed in theSemi-random g i 340/324 g g g ij Scanning mode in which raster scanningis performed l 315/18 in one of the vertical and horizontal directions II 0 mm whereas random scanning is conducted in the other 315/11, 12;178/DIG. 24, 7.7 direction [56] References Cited 6 Cl D F UNlTED STATESPATENTS 'awmg gums 2,595,646 5/l952 Doba, Jr. et al. 340/324 AD STORAGETUBE HORIZONTAL DEFLECTION CT.

HORIZONTAL COUNTER VERTICAL VIDEO AMPLIFIER DEFLECTION CT.

CRT DISPLAY SYSTEM WITH D-A CONVERTER CT.

HORIZONTAL AND VERTICAL SCAN PAIENIEU FEBI I 5 FIG.

MODE SELECTION CT.

BEAM CURRENT CONTROL CT.

BEAM ON/OFF CT.

STORAGE TUBE HORIZONTAL DEFLECTION CT.

HORIZONTAL COUNTER VERTICAL DEFLECTION CT.

VIDEO AMPLIFIER D A CONVERTER CT.

CRT DISPLAY SYSTEM WITH HORIZONTAL AND VERTICAL SCAN VERTICAL COUNTERFIG. 2

1 APPARATUS FOR DISPLAYING IMAGE INFORMATIONS This invention generallyrelates to. an apparatus for displaying image informations, and moreparticularly to a CRT display apparatus for alphanumeric and graphicpatterns in an information processing apparatus such as an electroniccomputer.

Generally speaking, there are two different methods in providingalphanumeric and graphic representations, that is, random scanning andraster scanning. In the random scanning the electron beam of the CRTtraces the contours of an alphanumeric or graphic pattern which is beingdisplayed. In the raster scanning the electron beam while beingdeflected, is intensitymodulated so as to give an alphanumeric orgraphic pattern on the phosphor screen of the CRT in the same manner asin the conventional television system.

In the random scanning, display commands are stored in a high-speedmemory device such as a core storage, and the display commands so storedare successively interpreted, thus finally producing appropriatedeflection signals in the form of electric current or potenial toprovide a desired pattern on the phosphor screen of the CRT.

It is necessary to read and display a single command repeatedly at arelatively high repetition rate, or specif ically more than thirty timesper second because otherwise, the appearance of flicker would beinevitable. In the random scanning process the preparation ofa chain ofcommands according to which a desired pattern is to be displayed on theCRT is much easier than in the ras- 'ter scanning process. Because achain of commands can be prepared'in the same mode of procedure as aperson draws pictures on a blackboard. The random scanning process,however, has the defects or disadvan tages as follows:

1. Exclusive use of an expensive high-speed memory device only forreproduction of images 2. Poor capability for displaying complexpatterns (Increase of the length of contour line beyond a certain limitwill be the cause for flicker.)

3. Requirement for a high speed deflection circuit which permits quickmovement of the electron beam to display complex patterns.

As seen for the points as listed above, the random scanning type displaysystem is inevitably expensive.

As for the raster scanning system, informations of intensity modulationof all the scanning lines of the raster of the CRT are stored in asequential memory such as a disk or a drum, and the informations thusstored are sequentially read out at a rate that causes no flicker effect(for instance, thirty times per second) on the CRT. In this imagedisplaying system, contrary to the random scanning system there is nolimit to the length of the contour of an image to be displayed, andtherefore no matter what a complicated pattern it may be, it will bedisplayed with high fidelity. Also, it is advantageous that a commercialtelevision set may be used without incorporating extra elaborateddeflection circuit, and therefore the raster scanning system isinexpensive.

The defects or disadvantages of this system, however, are as follows:

1. Time-wasting and difficult work required for preparing bit patternsaccording to which a desired pattern is to be displayed.

2. Storage capacity of a disk being too large, compared with thevideo-information of a single CRT. (Ordinarily ten or more CRTs are usedin association with a single disk with a view to making full use of thestorage capacity of the disk).

3. Simultaneous operation of CRTs of the number which makes full use ofthe storage capacity of a disk being impossible without using alarge-sized computer system 4. Expensive transmission lines, such ascoaxial cables being required for conveying video-signals from acomputer to the associated CRTs in instances where the CRTs are at adistant place from the computer.

The apparatus for displaying image informations according to thisinvention makes full use of the merits of both scanning systems.

More specifically, this invention uses in place of a disk, a storagetube in which an electron beam is used for reading or writing ofinformations. In such a storage apparatus the target plate is put in aproper condition to store a desired pattern upon the impingement of theelectron beam against the target, and the pattern thus stored can beread out in the form of electric signal by exposing the target to theelectron beam bombardment.

In instances where a storage tube is used as an image storage apparatus,the majority part of the deflection circuit may be used both for the CRTand the storage tube in common with each other, and this is advantageousfrom the economical point of view. The use and simultaneous operation ofa plurality of CRTs. for the reasons mentioned in above item (2) isunecessary.

Since one storage tube can be allotted to one CRT, a storage tube can bepositioned in the vicinity of the associated CRT, and therefore even ininstances where a computer is positioned at a distant place from the CRTthe transmission of write commands from the computer to the storage tubemay be performed at a low speed. Thus, no expensive transmission line isrequired.

Ordinarily, the writing" of information in the storage tube is conductedin the random scanning mode. As a matter of course this requires adeflection circuit capable of interpreting a chain of commands and ofgenerating deflection signals. Advantageously a single (ornon-repetative) drawing of the pattern suffices to the storage thereof,as is utterly different from the random scanning CRT. Therefore, thereis no problem for flickering, and any desired pattern can be stored nomatter what complex pattern it may be. The use of a high speeddeflection circuit will permit the substantial reduction of writingtime.

In contrast with this, the writing of informations in the storage tubecan be conducted in the raster scanning mode if the associateddeflection circuit is used both for reading and writing in common.

In operation, the storage tube is put into the writing condition at thetime when the deflection circuit deflects the electron beam to a placeon which the writing" is to be performed, and then the electron beam isallowed to impinge upon the target plate. Thus, the storage tubefunctions in the same way as the se quential memory.

As mentioned above, there are two different methods for carrying outwriting on the storage tube. In one method similar to sequentialstorage, writing" is performed at a selected time while the rasterscanning is ing is performed in a similar fashion to random accessmemory.

The inventors employs a totally new method for carrying out writing tothe target of the storage tube. In a storage tube it is possible tolocate a given point or position in terms of two-dimensionalcoordinates. Therefore, it is possible that one of the ordinates andabscissas is random-scanned whereas the other is raster-scanned to fix agiven point on the target of the storage tube. This new type scanningmethod is called hereinafter Semi-random Scanning". In an informationdisplaying apparatus according to this invention the informations arewritten in Semi-random Scanning mode. In the following explanationpertaining to Semi-random Scanning, simply for the benefit of simplicitythe raster scanning is used for the horizontal deflection whereas therandom scanning is used for the vertical deflection.

In the semi-random scanning system the conventional horizontaldeflection circuit can be used for the raster scanning withoutmodification. Assume that the repetition rate of horizontal deflectionis fl-I and that the number of abscissa points on a single horizontalline is N An N counter used is driven by clock pulses which are suppliedat the repetition rate of N X f,,,'and this counter generates anoverflow-pulse every time when the counter has counted N The horizontaldeflection circuit is'controlled by overflow pulses, which are used assynchronization pulse, and therefore the content of-the counter is anindication of the coordinate position of the deflected electron beam.

Assume that the number of horizontal lines is N the content of an N-counter is digital-to-analog converted in the form of electric currentor potential, which is used to deflect the electron beam in the verticaldirection. Thus, the random scanning in the vertical direction can beperformed by setting a desired number in the counter.

An N -counter may be a N, bit register. However, raster scanning isrequired in reading operation, and therefore a counting circuit if used,will perform reading as well as writing.

The relatively slow verticl scanning is performed by digital-to-analogconverting the content of the vertical counter. This drasticallyincreases the vertical writing speed, and at the same time facilitatesthe vertical writing, compared with the writing" by raster scanning. Itis adequate that the digital-to-analog converter which is used inwriting by Semi-random Scanning provides deflection current or potentialwithin the fly-- back time of the horizontal deflection saw tooth signal(approximately microseconds). Because of the relatively long time withinwhich the deflection current or potential is to be supplied, thedigital-to-analog converter is easily designed and constructed.

Still advantageously, the deflection circuit of the commercialtelevision set can be used as the horizontal deflection circuit in thedisplay apparatus of this invention without modification.

Thus, the deflection circuit in the display apparatus of this inventionusing the Semi-random Scanning is much simpler and less expensive thanthat in the display apparatus using the two-dimensional random scanning.The performance of the former is by no means inferior to that of thelatter, andfor instance in respect 0f the mode of blotting out whichwill be later described in detail, the former is superior to the latter.

As shown in FIG. 1, the main parts of the display apparatus of thisinvention using the Semi-random Scanning" are: a vertical counter, adigital-to-analog converter connected to the vertical counter, avertical deflection circuit connected to the digital-to-analog con-.verter, a vertical deflection circuit connected to thedigital-to-analog converter, a horizontal counter, a horizontaldeflection circuit connected to the horizontal counter, a storage tubefor storing image informations and a display CRT, and the verticaldeflection circuit and the horizontal deflection circuit are connectedto the storage tube. The CRT is connected to the horizontal counter, thedigital-to-analog converter and the storage tube.

In operation, the horizontal delfection circuit supplies a train ofsaw-tooth signals (horizontal deflection signals) to the storage tubeunder the control of horizontal synchronizing pulses from the horizontalcounter, thus causing the horizontal deflection of the electron beam inthe storage tube. The vertical deflection circuit functions todigital-to-analog convert the content of the vertical counter, thusgenerating vertical deflection signals which will cause the electronbeam to deflect in the vertical direction in the storage tube.

A mode selection circuit and a beam on/off circuit and a beam currentcontrol circuit are connected to the storage tube. The mode selectioncircuit is selectively set for one of writing, reading and erasing. Thebeam current control circuit permits the half-tone writing. The beamon/off circuit allows the electron beam to impinge upon the target atcontrolled intervals to perform writing or erasing, and the circuitallows the electron beam to continuously impinge upon the target for thesweeping period of the horizontal deflection to perform reading of thestored information.

A video-amplifier is connected between the storage tube and the displayCRT. The horizontal synchronizing pulses from the hroizontal counter andthe analog signals corresponding to the content of the vertical counterare applied to the deflection circuit of the display CRT, and at thesame time the image signals from the storage tube after amplified by thevideo-amplifier are supplied to the image circuit of the display CRT,thus causing the information stored in the storage tube to appear on theCRT.

In the display system of this invention a light-pen may be used toindicate a given coordinate point on the face plate of the storage tube.

This invention will be better understood from the 'follwong descriptionwhen considered in connection with the accompanying drawing in which:

FIG. 1 shows a block diagram of the whole system according to thisinvention; and

FIG. 2 is an explanatory representation as to how a given domain isdetermined on the display CRT.

Referring to FIG. 1, a mode selection circuit functions to control thevoltage which is applied to the targetof the storage tube, thus puttingthe storage tube in one of three different modes, Reading, Erasing andWriting. In a preferred embodiment using a Lithocon (trade name)produced by Princeton Electric Products Company the storage tube is putin the mode of Reading" by setting the target voltage at the level ofsix volts above the cathode voltage. Likewise, the

storage tube is put in the mode of Erasing by setting the target voltageat the level of twenty volts-above the cathode voltage, and in the modeof Writing by setting the target voltage at the level of 60 to 300volts.

In the mode of Reading, proper clock pulses are applied to thehorizontal counter, thus causing the same to, generate horizontalsynchronizing pulses. In instances where an ordinary television receiveris used for a display apparatus, clock pulsesare so controlled that therepetition rate of horizontal synchronizing pulses is equal to 15.75KHz. The horizontal synchr'o nizing pulses are applied to the horizontaldeflection circuit which is used to deflect the electron beam in thehorizontal direction. A horizontal deflection circuit of a videconcamera can be used without modification. Horizontal synchronizing pulsesare applied to the vertical counter as clock pulses. The verticaldeflection of the electron beam is performed by digital-to-analogconverting content of the vertical counter and by applying electricsignals thus obtained in the form of voltage or current to the verticaldeflection circuit after amplified. Thus, the.two-dimensional scanningcan be performed over the target of the storage tube (or theinformation-storing surface), and if a beam current is set for a propervalue by a beam current control circuit (for instance, by applying avoltage of a proper value to the first grid electrode of the storagetube), and if the electron beam of the proper value is allowed to ejectby setting the cathode voltage to zero, the stored'informations aresuccessively read" and finally they appear in the output of thevideo-amplifier. The horizontal synchronizing pulses and the electricsignals digital-toanalog converted from the content of the verticalcounter are applied to the deflection circuit of the CRT of thetelevision receiver, and at the same time the video-signals from thestorage tube are applied to the video-amplifier of the televisionreceiver, thus causing the information stored in the storage tube toappear on the CRT.

What is important in the display CRT is that: a particular storageposition of the information bearing surface or target of the storagetube exactly corresponds to a point of the information displayingsurface or phosphor screen of the CRT in one-to-one relationship. Thecontent 'of the horizontal counter and that of the vertical counter areshown in terms of the abscissa and ordinate of the co-ordinate systemrespectively.

In the mode of erasing informations from the storage tube, the modeselection circuit is set for that purpose. and the electron beam isallowed to scan the target surface of the storage tube for a fixed time(sufficient to supply the amount of electron beam which is requirred forerasing). If the electron beam is set at a relatively large value, theerasing time required will accordingly decrease.

In the mode of writing the mode selection circuit is set for writing,and thee beam current contron circuit is adjusted according to theintensity instruction, I

thus finally setting the electron beam of writing at a predeterminedvalue. In instances where an information is stored at either of blackand white levels, it suffices that the beam current control circuit isset for a predetermined state. Assume that the domain in whichinformations are to be stored is as large as the abscissa range H s H sH times the ordinate range V V & V as shown in FIG. 2. In view of thefact that the television scanning is performed in the descendingdirection, the ordinate is graduated increasingly in the same direction.First, the vertical counter is set at V and clock pulses are applied tothe horizontal counter. When the horizontal counter has counted upto Hthe electron beam is turned on, and when the counter has reached H -l-l,the electron beam is turned of thus performing a writing of informationat a predetermined intensity on the abscissa H, s H s H at the ordinateV A horizontal overflow pulse causes the count V of the vertical counterto increase by one, and then a similar operation is repeated. This isrepeated until the count V of the vertical counter reaches V thuscompleting writing of informations in the domain earlier mentioned.

In this mode ofwriting" informations can be stored, for instance on asingle horizontal line (y V if the vertical count is set at the fixednumber, and likewise, informations can be stored, for instance on asingle vertical line (x H if H is equal to H Apparently, an informationcan be stored, for instance on a single point (H V if H, and V, areequal to H and V respectively.

The writing of informations in the horizontal direction is allowed onlyat a selected time, as is the case in storing informations in asequential memory. In contrast to this, the writing of information inthe vertical direction is allowed at all times, as is the case instoring informations in a random access memory.

In a preferred embodiment of this invention the information stored onthe target of the storage tube can be selectively erased by first,putting the apparatus in the erasing condition and second, allowing theelectron beam to repeatedly trace a selected part of the storedinformation in the same fashion as the electron beam writes the selectedpart until the same disappears.

As is apparent from the above, irrespective as to in which modeofwriting, reading and erasing the apparatus operates, the horizontalcounter continuously performs counting under the control of clockpulses, generating horizontal synchronizing pulses at the repetitionrate of 15.75 KI-Iz. The horizontal deflection circuit of the televisionreceiver may be used for horizontal deflection of the electron beam inthe storage tube. As for the vertical deflection of the electron beam inthe storage tube the vertical deflection of the electron beam isperformed within the fly-back time of the horizontal scanning deflection(about 10 microseconds), and because of this relatively long timeallowable the digital-to-analog converter is easily designed, comparedwith that which would be required in random-scanning both in thevertical and horizontal directions. Because of the random-scanningemployed in one of the horizontal and vertical directions imageinformations can be stored at a high speed and with easiness, comparedwith the instances where image informations are stored in the sequentialmemory such as the disk.

As mentioned eariler, the television scanning system in which the lengthof a line to be drawn is not restricted, is advantageous to blottingoperation. The apparatus of this invention using Semi-random Scanning islikewise, advantageous to blotting operation. In the random scanningsystem it is very difficult for an electron beam to draw a line betweengiven two points in such an analogue way that the electron beam iscontinuously deflected at a given constant speed to draw a line betweengiven points. (If the deflection speed varies, the intensity of the linedrawn by the electron beam will accordingly vary.) ln the prior art, asa routine the line is drawn in the form of equivalent zigzag line, andif blotting is carried out in the random scanning system, it isnecessary to blot out adjacent points one after another, and thereforeordinarily much time is spent in blotting operation. In contrast withthis, the information displaying apparatus of this invention in which aline can be drawn at a high speed in the horizontal direction, willpermit the blotting operation to be performed at a high speed.

Still advangenously, since the vertical deflection is performed bydigital-to-analog converting the instantaneous content of the verticalcounter, the interlaced scanning can be conducted in a cmpletelycontrollable way. More specifically, the ordinary television system usesanalogue signal for vertical deflection in interlaced scanning, and thisis the cause for pairing. In contrast with this, in instances where thedeflection signals are produced by digital-to-analog convertinginstantaneous content of the counter, the deflection current isdetermined accurately or quantitatively and hence the interlacedscanning is stable, or free from pairing.

Although the embodiment is described as employing the raster-scanning inthe horizontal direction and the random-scanning in the verticaldirection it should be noted that the Semi-random Scanning can beperformed in the reversed way.

What is claimed is:

1. Apparatus for displaying image information comprising a memory deviceto write-in and read-out image information by addressing in terms of twocoordinates; a display device utilizing a scanning beam to display imageinformation, said memory device having an image information signal inputand-image information signal output, said display device having an imageinformation signal input; circuit means coupling the output of saidmemory device with the input of said display device to accomodatetransmission to the display de- -vice of signals representing imageinformation read-out from the memory device; addressing means associatedwith said memory device and operable to effect random access to onecoordinate of a given information and sequential access to the othercoordinate thereof; and scanning circuit means associated with saiddisplay device and operable to effect scanning movement of the displaydevice beam to reproduce an image corresponding to the image informationcontent of said image information signal, said display device scanningcircuit means being coupled to said addressing means for synchronizedoperation therewith.

2. Apparatus according to claim 1 wherein said memory device comprises astorage tube, and said addressing means comprises a scanning circuitwhich includes a vertical deflection circuit driven by adigital-toanalog converter circuit controlled by a digital counter, anda horizontal deflection circuit driven by a digital counter coupledthereto.

3. Apparatus according to claim 2 wherein the display device scanningcircuit means is coupled to said digitalto-analog converter circuit andcoupled to the digital counter that drives said horizontal deflectioncircuit.

4. Apparatus according to claim 3 wherein said horizontal deflectioncircuit is driven by overflow signals supplied by the digitalcountercoupled thereto.

5. Apparatus according to claim 3 including circuit means associatedwith said memory device and operable to selectively control the beamcurrent of the associated scanning beam, and to selectively set thememory device in any of a plurality of operating modes.

6. Apparatus according to claim 3 wherein the memory device scanningcircuit means is operable to effect random scanning in a verticaldirection and raster scanning in a horizontal direction.

1. Apparatus for displaying image information comprising a memory deviceto write-in and read-out image information by addressing in terms of twocoordinates; a display device utilizing a scanning beam to display imageinformation, said memory device having an image information signal inputand image information signal output, said display device having an imageinformation signal input; circuit means coupling the output of saidmemory device with the input of said display device to accomodatetransmission to the display device of signals representing imageinformation read-out from the memory device; addressing means associatedwith said memory device and operable to effect random access to onecoordinate of a given information and sequential access to the othercoordinate thereof; and scanning circuit means associated with saiddisplay device and operable to effect scanning movement of the displaydevice beam to reproduce an image corresponding to the image informationcontent of said image information signal, said display device scanningcircuit means being coupled to said addressing means for synchronizedoperation therewith.
 2. Apparatus according to claim 1 wherein saidmemory device comprises a storage tube, and said addressing meanscomprises a scanning circuit which includes a vertical deflectioncircuit driven by a digital-to-analog converter circuit controlled by adigital counter, and a horizontal deflection circuit driven by a digitalcounter coupled thereto.
 3. Apparatus according to claim 2 wherein thedisplay device scanning circuit means is coupled to said digital-to-analog converter circuit and coupled to the digital counter thatdrives said horizontal deflection circuit.
 4. Apparatus according toclaim 3 wherein said horizontal deflection circuit is driven by overflowsignals supplied by the digital counter coupled thereto.
 5. Apparatusaccording to claim 3 including circuit means associated with said memorydevice and operable to selectively control the beam current of theassociated scanning beam, and to selectively set the memory device inany of a plurality of operating modes.
 6. Apparatus according to claim 3wherein the memory device scanning circuit means is operable to effectrandom scanning in a vertical direction and raster scanning in ahorizontal direction.